FM-band transmitters find broad application in many types of wireless devices. Monolithic FM-band transmitters are particularly desired for mobile cellular devices given their compactness, reliability and low power consumption.
Designing the transmit power amplifier of an FM-band transmitter does not present a challenge for most applications. A power-efficient, nonlinear, switching power amplifier can be designed for the type of modulation the transmitter uses. However, a nonlinear power amplifier cannot be used in a mobile cellular device that is capable of communicating using FM and one or more other bands, e.g., Global System for Mobile Communications (GSM). Optimizing the efficiency of the nonlinear power amplifier for the FM band (i.e., about 76-108 MHz) degrades its performance in the other bands.